Method of making reinforced oval-form tubular screens



Aug. 25, 1970 P. W. FOURNIER METHOD OF MAKING REINFORCED OVAL-FORM TUBULAR SCREENS ori ina; Filed Dec. 11; 1967 4 rromvars United States Patent 3,525,139 METHOD OF MAKING REINFORCED OVAL-FORM TUBULAR SCREENS Paul W. Fournier, New Brighton, Minn., assignor to Universal Oil Products Company, Des Plaines, 111., a corporation of Delaware Original application Dec. 11, 1967, Ser. No. 689,555, now Patent No. 3,483,992, dated Dec. 16, 1969. Divided and this application June 24, 1969, Ser. No. 836,030

Int. Cl. B23p /16 US. Cl. 29-1635 1 Claim ABSTRACT OF THE DISCLOSURE RELATED APPLICATIONS This application is a division of my earlier filed application Ser. No. 689,555, filed Dec. 11, 1967, now Pat. No. 3,483,992, issued Dec. 16, 1969.

This invention is directed to providing a reinforced oval-form tubular screen which is of the type formed with a continuous slot from the helical winding of a continuous rod section around a plurality of spaced longitudinal rod members.

It is of course realized that unreinforced or open cylinder and tubular forms of slotted screen sections have been made heretofore for well screens, and the like, by the continuous helical winding of a rod or formed strip section around a cylindrical group of spaced apart longitudinally extending rods. The helically wound rod section is welded or otherwise fused to the longitudinal bars at each point of contact in order to provide a resulting tied-together relatively strong screen section. For screens of this general type, reference may be made to US. Patents, Nos. 2,046,456; 2,046,457; 2,046,458 and 3,101,- 526. As will also be noted in connection with the foregoing patents, a preferable form of screen makes use of triangular or wedge-shaped rod sections in the helical winding step so that self-cleaning types of cylindrical screens will be formed.

The present invention may be considered an improvement with respect to the aforedescribed types of screens, particularly where compressive and beam loads are involved. In other words, in certain installations the conventional circular or cylindrically shaped screens will be subjected to non-uniform compressive or crushing loads so that internal reinforcing is necessary. For example, in connection with tubular screen sections used within Water softening equipment, there is an oscillatory, non-uniform compressive force in a contact chamber from the water pressure acting upon a superimposed layer of sand or ionexchange material to lift the latter up and down.

One advantageous manner of precluding the crushing and/ or bending of tubular and cylindrical forms of screen sections is to provide internal webs or bar sections which can serve as stitfeners for the cylindrical wall section that is formed by the helically wound rod section. As will be subsequently set forth in more detail, various types and shapes of internal reinforcing members may be utilized within the scope of the present invention.

3,525,139 Patented Aug. 25, 1970 In any case, it may be considered a principal object of the present invention, to provide an internally reinforced form of oval-form tubular screen section, where the reinforcing member parallels the major axis of the oval-form section.

A further object of the present invention is to provide an overall screen construction or fabrication system such that the internal reinforcing web member extends in between spaced longitudinal rod members to thus be clamped in place by the interior edge portions of the continuous rod section which is helically wound to provide the slotted wall of the screen section.

Broadly, the present invention provides an improved internally reinforced oval-form tubular screen of the type having a continuous open slot construction and, in addition, provides a method for forming such screen unit in a manner which comprises, the steps of initially forming a circular tubular screen section by helically winding and attaching a continuous rod member around a plurality of separate spaced longitudinal rods, compressing the resulting helically wound tubular section and inserting along the major axis of such compressed section a longitudinal bar member having a predetermined depth snfiicient to provide a desired sized oval-form section, and then subsequently releasing the compressing action on such section to provide a tensile clamping of the interior wall portion of such section to the opposing edges of the inserted bar member whereby to provide a resulting oval-form tubular section.

A preferred construction and arrangement utilizes a non-circular form of continuous rod member to be helically wound around the spaced circular cluster of longitudinal rod members so that the resulting screen section is of a type considered to be non-clogging or self-cleaning. In other words, a triangularly shaped rod member, or one with a wedge-shaped cross-section, is used for the helically winding step to provide a resulting continuous helically slotted cylindrical or tubular screen section, with such slot in turn having an increasing area with respect to flow from the outer wall surface towards the inner wall surface of such resulting tubular section. In connection with the present internally reinforced tubular sections, it is preferred that the internally placed bar member, which will provide the reinforcing against external compressive forces, be positioned to be coextensive with the major axis and in a manner to be between spaced longitudinal rod members so that it is frictionally gripped by the inside wall of the helically wound rod member. The utilization of a wedge-shaped rod member, or at least one which has a non-circular cross-section, will provide, sharp interior corners or edges which can frictionally grip the inserted bar member as the compression on the tubular section is released in the forming operation. As a result welding or other fixed attachment means will be generally unnecessary for the resulting reinforced oval-form tubular section.

For the larger sizes of oval-form tubular sections, the internal reinforcing bar members will be provided with flange portions which will in turn provide lateral stability and preclude buckling under heavy load conditions. In other words, the reinforcing bar member may be of an I-beam configuration, or in the nature of a cross, such that there is lateral stability built into each reinforcing member to adequately suit structural requirements. Where desired, the internal reinforcing members may be designed along the lines of conventional structural beam members, taking into consideration the known static and dynamic load conditions to be encountered in the usage of the resulting oval-form tubular screen section. Adequate depth should be provided to insure that the outer fiber stresses are within the allowable limits for the metal to be used and for the loadings to be encountered. At the same time, the flange sections attached to the main bar member or wedge member should be of sufiicient width to preclude buckling. For example, the l/r ratio should be less than about 120 (with I being the length of the reinforcing bar member and r being the radius of gyration of such member).

Reference to the accompanying drawing and the following description thereof will serve to more clearly set forth the present invention and additional advantageous features which may be obtained in connection therewith.

DESCRIPTION OF THE DRAWING FIG. 1 is a sectional elevational view indicating an oval-form tubular screen section which may be formed inaccordance with the procedure of the present invention.

FIG. 2 indicates in a partial sectional view the use of a wedge shaped cross-section rod member in effecting the helical winding of the tubular screen section, as indicated by the lines 2-2 in FIG. 1 of the drawing.

FIG. 3 of the drawing indicates, in an isometric type view, an improved internally reinforced oval-form screen section wtih the use of a modified form of cross bar member.

FIG. 4 of the drawing indicates diagrammatically a still further modified form of an internal reinforcing which may be used in an oval-form spiral wound tubular screen section.

Referring now particularly to FIGS. 1 and 2. of the drawing, there is shown a tubular form screen section 1 which has been formed in accordance with the teachings of the aforementioned patents, with a continuous wedge shaped rod section 2 being helically wound around a circular or tubular configuration of spaced longitudinal rod members 3. As noted in the prior art, a preferred construction or fabrication system provides for the fusing of the rod section 2 with each of the longitudinal rod members 3 at each point of contact. Generally, the fusing or attachment is provided by electrical resistance so as to, in effect, provide spot welding of the touching ro'd members. The result is a structurally strong, tied-together, cylindrical form screen section. The slots or open spacer 4 formed by rod 2 may be adjusted during the fabrication operation so as to, in turn, provide a continuous helical slot of a desired width. Also, as noted in FIG. 2, by having the wide portion of the rod member 2 to the exterior of the resulting tubular screen section there will be a resulting increasing sized fluid passageway for the slot 4, with respect to out-to-in fiow through the tubular screen section. On the other hand, where it is desired to have an in-to-out fluid flow for any particular tubular screen section, then the rod member 2 may be wound in a manner to have the wider portion of the trapezoidal or triangularly shaped section along the inside wall of the resulting tube section whereby there is a resulting helical slot increasing in cross-section in the in-to-out direction.

In accordance with the present invention, after the com pletion of the circularly formed tubular screen section by the helical winding operation, there is a compression of such section by laterally opposing clamps or holding members 5 so as to make an elliptical or oval-form crosssection of the tubular screen unit. The holding or clamping means 5 are indicated diagramamtically in FIG. 1 as being capable of moving in and out from opposing wall portions of the tubular screen section 1 and thus provide a convenient easy means of inserting a bar member 6. It is, of course, not intended to limit the present invention to any one form of clamping or 'holding means or to any one mechanical arrangement for effecting the lateral compression and oval-forming step. However, preferably the clamping means 5 will be power operated and easily controlled and regulated to provide fine adjustment of the squeezing action on the tubular section 1.

While the tubular section 1 is being held in the compressed position by clamping means 5 then a long bar section, such as 6, is inserted across the major access of the resulting elliptical or oval-form tubular member, be-

ing placed such that the end portions 6' will be spaced in between adjacent longitudinal rod members 3. With the bar member 6 longitudinally in place for the full length of the tubular section 1, the side compressive forces provided by clamp means 5 are released and the inside wall portion of the tubular section 1, as provided by the interior edges of the continuous helically Wound rod section 2, will effect a tight clamping against the bar edges at each end portion 6. In practice, it has been found entirely unnecessary to effect any welding, bolting or other special attachment means for the internal reinforcing of the resulting oval-form tubular section. This is particularly true where the helically wound rod member is of a noncircular form and has internal sharp edge portions, such as may be provided with a rod member that is of a wedge shape or has a triangular cross-section.

The embodiment of FIG. 1 indicates that the bar member 6 is provided with laterally extending flange portions 7 such that there is adequate lateral stability to preclude buckling of such bar member 6 under beam-like loadings which will be encountered in a particular commercial operation. Again, it should be noted that the flange sec tions 7 shall be of sufficient width and thickness to provide a desired radius-of-gyration for the I-beam like section 6 but, at the same time, shall be set back from the bar edges 6' sufliciently to preclude contact or interference with longitudinal rod members inside of the tubular section 1.

In FIG. 3 of the drawing there is indicated compression means to provide an oval-form tubular section 8 which has been initially formed by the helical winding of the continuous rod member 12 (preferably of wedge shape) around a spaced cluster of longitudinal rod members 9. In this instance, the internal reinforcing is provided with a cross form of bar members, one bar member 10 has a width (or height) sufficient to extend in a plane coextensive with a major axis of the oval or elliptical form tube section 8 and in turn provide the resulting oval-form section of a desired size. At the same time, laterally projecting flange sections 11 extend at right angles with respect to the vertical bar member 10 so as to provide a sufficient l/r ratio in the finished section and stability against buckling under load conditions. Where desired, the width of flange sections 11 may be sufficient to substantially reach and contact the internal wall surface of the resulting oval-form tubular section. In all instances, the internal bar members shall be positioned or located so as to fall between spaced longitudinal rod members 9 and be capable of being directly clamped by the internal edges of the continuous helical rod member 12 forming tube section 8.

Also in connection with FIG. 3 of the drawing, it may be noted that suitable spaced holes 13 are provided through the outwardly projecting flange section 11 such that fluid flow may be readily permitted through such internal reinforcing sections and provide a minimum of interference with fluid flow into or from an elongated tubular screen section. Where deemed desirable for hydraulic purposes additional holes may be provided at spaced points along the entire length of the vertically indicated bar member 10.

In FIG. 4 of the drawing there is indicated still another form of internal reinforcing which may be used to advantage in a completed oval-form tubular screen section. In this instance a bar member 14 is provided for extension along or across the major axis of the resulting oval-form tubular section, such as in FIGS. 1 and 3 of the drawing. However, in the present embodiment there are provided hemispherical, or half, sections of pipe 15 which may be welded or otherwise attached to the vertically indicated bar section 14 so as to provide Web reinforcement for such bar section. In other words, the curved or half round sections 15 shall be of a radius and of a thickness sufiicient to provide suitable width and radiusof-gyration to the composite beam-like section, whereby the resulting reinforced tubular screen section will have adequate lateral stability, along width depth, to preclude buckling and excessive fiber stresses under the load conditions to be encountered.

It will be obvious to structural engineers that various forms of reinforcing or flanging for various types of I-beam type bar members may be provided to suit varying load conditions and that such beams may in effect follow conventional structural design practices. However, in accordance with the present invention, it is preferred that each of the reinforcing internal bar sections have sharp or conventional square corner edges which, in turn, can be gripped and clamped by the multiplicity of contacting edges provided by the helical winding of a wedge-shape form of rod member forming the inside wall of the resulting oval-form tubular screen section. This, of course, results in a tight clamping or gripping .of each internal reinforcing bar member so as to preclude the need for welding, bolting or other mechanical clamping means in the finished oval-form tubular sections.

It is not intended to limit the present invention to any one tubular size, inasmuch as major diameters for small tubular screen sections may be of the order of 1" to 2" while larger tubular sections may be up to three or four feet or more. Still further, it is to be realized that the resulting oval-form tubular sections maybe fabricated of many types of materials including plastics, fiber glass, copper, brass, stainless steel or other alloys, and the like. Where it is desired to use a tubular screen section internally within a chamber as a distributor or collector tube, then suitable connecting pipe nipples or flanges may of course be fitted to the end portions of the resulting ovalformed tubular sections such that conventional piping or nozzles may be connected with such sections. Where a flange or an end plate is utilized on a tubular screen section, then the appropriate end portions of the internal reinforcing bar members may be notched or chamfered to provide for suitable juncture with the flange means or with any end plates that may be desired for such particular screen unit.

I claim as my invention:

1. A method for forming an oval-form tubular screen unit which comprises the steps of initially forming a circular tubular screen section by helically winding a continuous rod member around a plurality of separate circumferentially spaced longitudinal rods of predetermined length, fixedly attached the resulting helically wound rod to said longitudinal rods at their points of contact to form a structurally strong helically wound tubular section, laterally compressing said helically wound tubular section and inserting acrossa major axis of the resulting elliptical section, and between adjacent longitudinal rods, a longitudinal bar member having a depth greater than the normal non-deformed inside diameter of said circular section as provided by the helically wound rod portion, and subsequently releasing the compressing action on said section to provide a tensile clamping of the interior wall portion of said helically wound continuous rod member to and in direct contact with the opposing edges of said bar member, said helical continuous rod member having a wedge shaped cross-section and a flat edge facing the interior of the resulting tubular screen section whereby the internal edge thereof will clamp tightly to the outer edge portions of said longitudinal bar member upon the releasing of the compressive action of said tubular section.

References Cited UNITED STATES PATENTS 806,416 12/1905 Layne 166--231 2,046,458 7/1936 Johnson 210497.1 X 2,081,198 5/1937 Hahn.

2,126,938 8/1938 Williams et al. 210-497. X 2,383,672 8/1945 Neisingh 210-497.1 X 3,101,526 8/1963- Paullus et a1. 29163.5 3,348,303 10/1967 Umeda 29-453 X FOREIGN PATENTS 5,552 6/ 1913 Great Britain.

JOHN F. CAMPBELL, Primary Examiner V. A. DIPALMA, Assistant Examiner US. Cl. X.R. 

